[Sass] Mixin a mixin-arg error-handling bug.

doc-src/SASS_CHANGELOG.md

@@ -3,6 +3,11 @@
 * Table of contents
 {:toc}
 
+## 3.0.3 (Unreleased)
+
+* Raise an informative error when mixin arguments have a mispaced comma,
+  as in `@include foo(bar, )`.
+
 ## 3.0.2
 
 [Tagged on GitHub](http://github.com/nex3/haml/commit/3.0.2).

lib/sass/script/parser.rb

@@ -271,7 +271,7 @@ RUBY
       def arglist
         return unless e = interpolation
         return [e] unless try_tok(:comma)
-        [e, *arglist]
+        [e, *assert_expr(:arglist)]
       end
 
       def raw
@@ -333,6 +333,7 @@ RUBY
       EXPR_NAMES = {
         :string => "string",
         :default => "expression (e.g. 1px, bold)",
+        :arglist => "mixin argument",
       }
 
       def assert_expr(name)

test/sass/scss/scss_test.rb

@@ -1022,6 +1022,20 @@ $value : bip;
 foo {
   bar: -moz-\#{$value};
 }
+SCSS
+  end
+
+  def test_extra_comma_in_mixin_arglist_error
+    assert_raise(Sass::SyntaxError, <<MESSAGE) {render <<SCSS}
+Invalid CSS after "@include foo(bar, ": expected mixin argument, was ")"
+MESSAGE
+@mixin foo($a1, $a2) {
+  baz: $a1 $a2;
+}
+
+.bar {
+  @include foo(bar, );
+}
 SCSS
   end
 end